For road building and constructing new sports grounds and the like the subsurface is currently provided temporarily with a sand pack. This serves the purpose of making the weight of the sand compact the subsurface. In this process the sand pack presses the water out of the subsurface and compresses the mass of the subsurface. After the desired compaction of the subsurface has occurred, the sand pack is removed again, after which, depending on the envisaged final use, the subsurface can be asphalted, turfed or the like.
The disadvantage here is that large quantities of sand have to be brought in, because a sand pack which is one metre or more thick is often required for this method. It is very labour-intensive to apply this sand pack. Such a sand pack then has to remain there for a long time, in particular between 90 and 450 days, in order to achieve the desired compaction. Finally, the large quantity of sand has to be removed again before the envisaged road, sports ground or the like can be constructed further. All in all, this compacting method is an expensive, laborious and time-consuming process.
As an alternative to the abovementioned method, a different type of compacting body, such as a roller, can also be used for compacting the subsurface. Various rollers with which subsurfaces can be compacted are known. Such rollers generally consist of a metal roller cylinder which is rotatable about a rotary shaft forming part of a vehicle. On top of its own weight, the rolling cylinder is further loaded by a part of the weight of the vehicle. If desired, the roller cylinder is also made heavier from the inside in order to add weight.
For example, U.S. Pat. No. 3,662,657 discloses a turf roller for a tractor, in which cylindrical roller bodies which can replace the rear wheels of the tractor are used. In this case each roller body comprises a roller cylinder containing a concentric water compartment which is filled with water. The roller bodies comprise a central hollow around the axis, by means of which they can be mounted on the respective wheel hubs. The compartment is not filled with water until after the roller bodies have been mounted on the wheel hubs.
The disadvantage here again is that these roller bodies weighted with fluid are still relatively large and are consequently difficult to handle. For types of applications other than rolling turf, such as the abovementioned road building, constructing sports grounds and the like, a greater roller pressure is often required. This would increase the size of a roller according to U.S. Pat. No. 3,662,657 and consequently make the roller even more difficult to handle.